FLAC is a format which guarantees lossless data preservation. FLAC
does not guarantee a specific or consistent compression ratio. If
you are looking for a guarantee that the compression ratio is
repeatable, then you are looking in the wrong place.
While it is probably true that the same executable will produce the
same FLAC file from the same source file on different PCs, I'm not
sure there isn't any run-time variation based on processor type.
A better approach for you would be to modify your expectation to be
that the compression ratios fall into a range of values, rather than
expect them to be precise. Keep in mind that FLAC is focused on
guaranteeing that the final uncompressed audio samples precisely
match the original audio samples, while secondary concerns such as
the intermediate compression ratio are not guaranteed at all. You
might be able to find repeatable experiments, but it does not change
the fact that FLAC does not have a pre-defined compression ratio.
Brian Willoughby
Sound Consulting
On May 23, 2011, at 09:46, Eri Eri wrote:> I?m investigating together with Fernando Marengo, and I think our
> doubt might have been misunderstood.
> Let?s say that we have a certain version of Flac (1.2.1 for
> example) and a certain track (?The blue room.wav? for example). If
> we were to compress that same track on different PCs using exactly
> the same Flac executable and command line parameters, would we
> always get exactly the same (bit-by-bit) output file?
>
> Differences in the output files yield different compression ratios.
> We want to make sure our results are consistent and repeatable so
> answering that question is crucial.
